Cardiovascular magnetic resonance myocardial feature tracking detects quantitative wall motion during dobutamine stress

Background: Dobutamine stress cardiovascular magnetic resonance (DS-CMR) is an established tool to assess hibernating myocardium and ischemia. Analysis is typically based on visual assessment with considerable operator dependency. CMR myocardial feature tracking (CMR-FT) is a recently introduced technique for tissue voxel motion tracking on standard steady-state free precession (SSFP) images to derive circumferential and radial myocardial mechanics. We sought to determine the feasibility and reproducibility of CMR-FT for quantitative wall motion assessment during intermediate dose DS-CMR. Methods: 10 healthy subjects were studied at 1.5 Tesla. Myocardial strain parameters were derived from SSFP cine images using dedicated CMR-FT software (Diogenes MRI prototype; Tomtec; Germany). Right ventricular (RV) and left ventricular (LV) longitudinal strain (Ell(RV) and Ell(LV)) and LV long-axis radial strain (Err(LAX)) were derived from a 4-chamber view at rest. LV short-axis circumferential strain (Ecc(SAX)) and Err(SAX); LV ejection fraction (EF) and volumes were analyzed at rest and during dobutamine stress (10 and 20 mu g . kg(-1) . min(-1)). Results: In all volunteers strain parameters could be derived from the SSFP images at rest and stress. Ecc(SAX) values showed significantly increased contraction with DSMR (rest: -24.1 +/- 6.7; 10 mu g: -32.7 +/- 11.4; 20 mu g: -39.2 +/- 15.2; p < 0.05). Err(SAX) increased significantly with dobutamine (rest: 19.6 +/- 14.6; 10 mu g: 31.8 +/- 20.9; 20 mu g: 42.4 +/- 25.5; p < 0.05). In parallel with these changes; EF increased significantly with dobutamine (rest: 56.9 +/- 4.4%; 10 mu g: 70.7 +/- 8.1; 20 mu g: 76.8 +/- 4.6; p < 0.05). Observer variability was best for LV circumferential strain (Ecc(SAX)) and worst for RV longitudinal strain (Ell(RV)) as determined by 95% confidence intervals of the difference. Conclusions: CMR-FT reliably detects quantitative wall motion and strain derived from SSFP cine imaging that corresponds to inotropic stimulation. The current implementation may need improvement to reduce observer-induced variance. Within a given CMR lab; this novel technique holds promise of easy and fast quantification of wall mechanics and strain.